12 research outputs found
Optimized âCanopyâ Albedo of Vegetated Land Surfaces and its Effect on Simulated Productivity and Climate0021
Description and validation of the Simple, Efficient, Dynamic, Global, Ecological Simulator (SEDGES v.1.0)
In this paper, we present a
simple dynamic global vegetation model whose primary intended use is
auxiliary to the landâatmosphere coupling scheme of a climate model,
particularly one of intermediate complexity. The model simulates and provides
important ecological-only variables but also some hydrological and surface
energy variables that are typically either simulated by land surface schemes
or else used as boundary data input for these schemes. The model formulations
and their derivations are presented here, in detail. The model includes some
realistic and useful features for its level of complexity, including a
photosynthetic dependency on light, full coupling of photosynthesis and
transpiration through an interactive canopy resistance, and a soil organic
carbon dependence for bare-soil albedo. We evaluate the model's performance
by running it as part of a simple land surface scheme that is driven by
reanalysis data. The evaluation against observational data includes net
primary productivity, leaf area index, surface albedo, and diagnosed
variables relevant for the closure of the hydrological cycle. In this setup,
we find that the model gives an adequate to good simulation of basic
large-scale ecological and hydrological variables. Of the variables analyzed
in this paper, gross primary productivity is particularly well simulated. The
results also reveal the current limitations of the model. The most
significant deficiency is the excessive simulation of evapotranspiration in
mid- to high northern latitudes during their winter to spring transition. The
model has a relative advantage in situations that require some combination of
computational efficiency, model transparency and tractability, and the
simulation of the large-scale vegetation and land surface characteristics
under non-present-day conditions